Dimethylphenylsilylmethylpolysilane and method for producing the same

ABSTRACT

A dimethylphenysilylmethylpolysilane is prepared by condensating 1,1-dichloro-1,2,2-trimethyl-2-phenyldisilane in the presence of an alkali metal or alkali earth metal, in an aprotic solvent. This polymer is a viscous liquid which has a weight average molecular weight in the range of from 5,000 to 500,000 and a narrow molecular weight distribution, and has various uses as electroconductors, photoresist and optical information recording materials.

BACKGROUND OF THE INVENTION

(1) Field of the Invention

This invention relates to a novel compound,dimethylphenylsilylmethylpolysilane, being usable as materials forelectroconductor, photoresist, optical information recording materialand the like, and a method for producing the same.

(2) Description of the Prior Art

As the method for producing the polysilane compound, The Journal ofAmerican Chemical Society, Vol. 71, page 963 (1949) and ChemistryLetters, page 551 (1976) disclose each the method for producing a chainor cyclic dimethylpolysilane having a repeating unit expressed by thefollowing formula: ##STR1## wherein, Me is methyl, by reactingdichlorodimethylsilane with sodium metal in benzene or xylene.

Further, U.S. Pat. No. 4,260,780 discloses the process for obtainingphenylmethylpolysilane, represented by the following formula: ##STR2##wherein, Me is methyl, Ph is phenyl, the ratio of x to y is 1:3 to 1:20,and z is an integer ranging from 1 to 100, by reactingdichlorodimethylsilane with dichloromethylphenylsilane in the presenceof an alkali metal in a solvent of xylene, tetrahydrofuran or the like.

However, the conventional polysilanes, as shown in the abovementionedformula (1) or (2), are all built up of a principal chain comprising asilicon-silicon bond and substituents, namely methyl and phenyl groups,introduced into said principal chain. Among them, accordingly, can neverbe found polysilanes which comprise introducing dimethylphenylsilylgroup as proposed by this invention.

It is one object of this invention, therefore, to provide a noveldimethylphenylsilylmethylpolysilane constructed so as to introduce thesubstituents such as dimethylphenylsilyl and methyl groups into theprincipal chain comprising the silicon-silicon bond.

Another object of the invention is to provide a method for producingdimethylphenylsilylmethylpolysilane.

Other objects and advantages will be apparent from the accompanyingdisclosure.

SUMMARY OF THE INVENTION

This invention provides dimethylphenylsilylmethylpolysilane whichcomprises a repeating unit represented by the following formula [I]:##STR3## wherein, Ph is phenyl, and Me is methyl, and has a weightaverage molecular weight in the range of from 5,000 to 500,000.

The dimethylphenylsilylmethylpolysilane according to this invention canbe prepared by reacting disilane having the following formula [II]:

    PhMe.sub.2 SiSiCl.sub.2 Me                                 [II]

wherein, Ph is phenyl, and Me is methyl, with an alkali metal or alkaliearth metal.

The disilane [II], starting material for the polymer of this invention,can be obtained by reacting 1,1,2-trichloro-1,2,2-trimethyldisilane withphenylmagnesium halide in the presence of a transition metal catalystother than cobalt as disclosed in U.S. Ser. No. 011,804 filed on Feb. 6,1987.

One reactant of this reaction, namely1,1,2-trichloro-1,2,2-trimethyldisilane, can be obtained from thedisilane fraction by-produced when synthesizing dichlorodimethylsilanefrom methyl chloride and silicon metal.

DETAILED DESCRIPTION OF THE INVENTION

According to this invention, the disilane [II] and the alkali metal oralkali earth metal are reacted in the aprotic solvent such, forinstance, as a solvent of n-pentane, n-hexane, benzene, toluene ortetrahydrofuran. As an alkali metal, lithium, sodium, potassium and thelike are utilized, and as an alkali earth metal, magnesium, calcium orthe like are utilized. Among them, lithium, and magnesium are especiallypreferable.

The amount of alkali metal or alkali earth metal used is required to beat least two equivalent, normally two to three equivalent, per oneequivalent of disilane [II].

As reaction temperatures, optional ones in the range of from more than0° C. to less than the boiling point of a reaction solvent used areemployed. Reaction is completed by heating a reaction mixture to theboiling point of the reaction solvent at a proper time after start ofthe reaction. The reaction time somewhat varies dependent upon thereaction solvent and reaction temperatures used. Generally speaking,however, the reaction completes in 1 to 5 hours.

After completion of the reaction, a reaction product is refined in ausual manner for refining polysilanes, for instance a manner ofrepeating reprecipitation by the use of benzene and alcohol or the like,thereby obtaining the dimethylphenylsilylmethylpolysilane of thisinvention.

This invention has found that by selecting the disilane [II] as thestarting material and condensing the same in the presence of the alkalimetal or alkali earth metal, there can be obtained a noveldimethylphenylsilylmethylpolysilane constructed so as to introduce thesubstituents such as dimethylphenylsilyl and methyl groups into theprincipal chain comprising the silicon-silicon bond.

The dimethylphenylsilylmethylpolysilane according to this invention, ischaracterized by that it has a weight average molecular weight (Mw)ranging from 5,000 to 500,000 and a narrow distribution of molecularweight as is supported by the fact that the ratio of weight averagemolecular weight (Mw) to number average molecular weight (Mn), namelyMw/Mn, is 1.6. The polymer to be provided by this invention has varioususes as raw materials for making electroconductors, photoresist, opticalinformation recording materials and the like.

EXAMPLE 1

The inside of a 1-liter, 3-neck flask fitted with a condenser, droppingfunnel, thermometer and stirrer was replaced by argon. Thereafter, 300 gof toluene and 23 g (1 mole) of sodium were fed thereto, and a toluenesolution of 124.5 g (0.5 mole) of1,1-dichloro-1,2,2-trimethyl-2-phenyldisilane was dropped in the samewith stirring at a reaction temperature of from 30° to 50° C. in 1 hour.After completion of dropping, the reaction mixture was heated graduallyand was allowed to react for 3 hours while refluxing. Then, theresulting reaction product was cooled to a room temperature, theby-produced sodium salt was separated by filtration, and the filtratewas concentrated by distilling out the toluene. The concentratedfiltrate was added with 300 ml of benzene, and further added with 1liter of methanol with stirring. This mixture was left standing tothereby obtain a polysilane layer as a bottom layer. This bottompolysilane layer was recovered and further the solvent remaining underreduced pressure was removed completely to thereby obtain 57.9 g of aviscous liquid dimethylphenylsilylmethylpolysilane. Yield was 65%. Theresults obtained from analysis of the product are as shown below:

Proton nuclear magnetic: resonance spectrum (60 MHz, CDCl₃); δ ppm=0.3(Broad, Si-Me), 7.2 (Broad, Si-Ph) Me-Ph (Proton ratio)=9/5.1.

Infrared absorption spectrum (cm⁻¹): 3050, 2950, 2890, 2070, 1950, 1875,1810, 1580, 1480, 1420, 1400, 1240, 1100.

Ultraviolet absorption spectrum (nm): 275.

Gel permeation chromatography: Measuring conditions: Column pressure: 30kg/cm², Flow rate: 1.25 ml/min.,

Column: TSK Gel GMH6, 7.5 mm×60 cm, Eluent: Tetrahydrofuran; Weightaverage molecular weight (Mw)=78,000; Mw/Mn=1.6.

EXAMPLE 2

By using the same apparatus as Example 1, a tetrahydrofuran solution of124.5 g (0.5 mole) of 1,1-dichloro-1,2,2-trimethyl-2-phenyldisilane wasdropped in a mixture of 300 g of tetrahydrofuran and 7 g (1 mole) oflithium at a reaction temperature of from 0° to 15° C. in 1 hour.Thereafter, the same was allowed to react for 3 hours while refluxing.Then, the resulting reaction product was treated according to the sameprocedure as Example 1 to thereby obtain 59.7 g of a viscous liquiddimethylphenylsilylmethylpolysilane. Yield was 67%. The results obtainedfrom analysis of the product are as shown below:

Proton nuclear magnetic: resonance spectrum (60 MHz, CDCl₃); δ ppm=0.3(Broad, Si-M3); 7.2 (Broad, Si-Ph); Me/Ph (Proton ratio)=9/5.1.

Infrared absorption spectrum (cm⁻¹): 3050, 2950, 2890, 2070, 1950, 1875,1810, 1580, 1480, 1420, 1400, 1240, 1100.

Ultraviolet absorption spectrum (nm): 275.

Gel permeation chromotography: Measuring conditions: The same asutilized in Example 1; Weight average molecular weight (Ms)=50,000;Mw/Mn=1.6.

We claim:
 1. A dimethylphenylsilylmethylpolysilane having a repeatingunit represented by the formula [I] and having a weight averagemolecular weight of from 5,000 to 500,000: ##STR4## wherein, Ph isphenyl and Me is methyl.
 2. The dimethylphenylsilylmethylpolysilaneaccording to claim 1 in which the ratio of weight average molecularweight to number average molecular weight is 1.6.
 3. A method forproducing a dimethylphenylsilylmethylpolysilane having a repeating unitrepresented by the formula [I]: ##STR5## wherein, Ph is phenyl and Me ismethyl, and having a weight average molecular weight of from 5,000 to500,000, which comprises the step of condensating1,1-dichloro-1,2,2-trimethyl-2-phenyldisilane represented by the formula[II]:

    PhMe.sub.2 SiSiCl.sub.2 Me                                 [II]

wherein, Ph is phenyl and Me is methyl, in the presence of an alkalinemetal or alkali earth metal, in an aprotic solvent.
 4. The methodaccording to claim 3 in which 2 to 3 equivalents of said alkaline metalor alkali earth metal are used per 1 equivalent of said1,1-dichloro-1,2,2-trimethyl-2-phenyldisilane represented by the formula[II].
 5. The method according to claim 3 in which said aprotic solventis any one of n-pentane, n-hexane, benzene, toluene and tetrahydrofuran.6. The method according to claim 3 in which said alkali metal is lithiumor sodium.
 7. The method according to claim 3 in which said alkalineearth metal is magnesium.